1. Technical Field
The present invention relates to a projector which displays an image on a projection surface.
2. Related Art
When a projector is used to cause an image whose image bounds form a rectangle to be displayed on a projection surface of a screen or the like, depending on a relative positional relationship between the projector and the projection surface, it may happen that the image bounds of the image displayed on the projection surface (hereafter referred to also as the “projection image”) are distorted into a trapezoid. In this kind of case, a keystone correction is used which corrects a distortion of the projection image (hereafter referred to also as a “keystone distortion”).
Heretofore, in the projector, as a function of performing the keystone correction, there have been a function of manually performing the keystone correction (hereafter referred to also as a “keystone manual correction”), and a function of automatically performing the keystone correction (hereafter referred to also as a “keystone automatic correction”). When the keystone manual correction function is used, a user, by operating an operation button or the like included in the projector while observing the image bounds of the image projected onto the screen, and gradually changing the shape of image bounds generated on a liquid crystal panel, implements the keystone correction in such a way that the shape of the image bounds of the image projected becomes rectangular (refer to, for example, JP-A-2006-54824).
On the other hand, when the keystone automatic correction function is used, the projector, by imaging an image projected onto the screen by means of, for example, a camera included in the projector and, based on the image imaged, calculating a tilt of the projection axis of the projector with respect to the screen, automatically implements the keystone correction in such a way that the shape of the image bounds of the projection image becomes rectangular. The keystone automatic correction is started by, for example, the user operating the operation button included in the projector.
Even in the case in which the projector includes the keystone automatic correction function, there has been a case in which the user is not aware of that function because the keystone automatic correction is not started unless the user operates the operation button, as heretofore described. In the event that the user is not aware of the keystone automatic correction function, as the user implements the keystone manual correction while observing the image bounds of the image projected onto the screen in the way heretofore described, it takes a lot of trouble, and it takes time until an image whose image bounds form a rectangle is displayed on the screen, causing inconvenience.
This kind of problem has been a problem common not only to a case of implementing a keystone correction in the projector, but also to a case of adjusting a projected image in accordance with a relative positional relationship between the projector and the projection surface in a case of adjusting a focus, in a case of carrying out an enlargement and reduction (zoom) adjustment, or the like.